[PATCH] MIPS: add smp_call_function_single()

[Stephane Eranian <eranian@hpl.hp.com>]

    [MIPS] add smp_call_function_single()
    
    signed-off-by: Stephane Eranian <eranian@hpl.hp.com>
    signed-off-by: Phil Mucci <mucci@cs.utk.edu>

diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index be7362b..9e376e2 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -193,6 +193,53 @@ void smp_call_function_interrupt(void)
 	}
 }
 
+int smp_call_function_single(int cpu, void (*func) (void *info), void *info, int retry,
+			     int wait)
+{
+  struct call_data_struct data;
+  int me = smp_processor_id();
+
+  /*
+     * Can die spectacularly if this CPU isn't yet marked online
+      */
+  BUG_ON(!cpu_online(me));
+  if (cpu == me) {
+    WARN_ON(1);
+    return -EBUSY;
+    }
+
+  /* Can deadlock when called with interrupts disabled */
+  WARN_ON(irqs_disabled());
+
+  data.func = func;
+  data.info = info;
+  atomic_set(&data.started, 0);
+  data.wait = wait;
+  if (wait)
+    atomic_set(&data.finished, 0);
+
+  spin_lock(&smp_call_lock);
+  call_data = &data;
+  mb();
+
+  /* Send a message to the other CPU */
+  core_send_ipi(cpu, SMP_CALL_FUNCTION);
+
+  /* Wait for response */
+  /* FIXME: lock-up detection, backtrace on lock-up */
+  while (atomic_read(&data.started) != 1)
+    barrier();
+
+  if (wait)
+    while (atomic_read(&data.finished) != 1)
+      barrier();
+  call_data = NULL;
+  spin_unlock(&smp_call_lock);
+
+  return 0;
+}
+EXPORT_SYMBOL(smp_call_function_single);
+
 static void stop_this_cpu(void *dummy)
 {
 	/*
diff --git a/include/asm-mips/smp.h b/include/asm-mips/smp.h
index 13aef6a..5acbf38 100644
--- a/include/asm-mips/smp.h
+++ b/include/asm-mips/smp.h
@@ -102,6 +102,8 @@ static inline void smp_send_reschedule(int cpu)
 	core_send_ipi(cpu, SMP_RESCHEDULE_YOURSELF);
 }
 
+extern int smp_call_function_single(int cpuid, void (*func) (void *info),
+				void *info, int retry, int wait);
 extern asmlinkage void smp_call_function_interrupt(void);
 
 #endif /* CONFIG_SMP */